JPS6286085A - Afterglow phosphor - Google Patents

Abstract

PURPOSE:To provide a long-afterglow blue phosphor which is excellent in afterglow characteristics, luminescence brightness, burning properties and current characteristics and is blue in both luminescent and afterglow colors, which comprises (Zn, Cd)S as a matrix, Ag as an activator, Ga, In, etc. as a first co-activator, and Cl, Br, Al, etc. as a second co-activator. CONSTITUTION:Raw materials are weighed in such amounts as will provide a phosphor comprising a matrix comprised of (Zn, Cd)S contg. 0.1-20% CdS (in terms of wt. based on a matrix comprised of a sulfide; the same applies hereinafter), 1X10<-5>-1X10<-1>% Ag as an activator, 0-3X10<-1>% at least one member selected from among Ga, In, Tl, Sn, As, Pb, Sb, Bi, and P as a first co-activator, 5X10<-5>-5X10<-1>% at least one member selected from among Cl, Br, I, F, and Al as a second co-activator and, if necessary, 5X10<-4>-5X10<-2>% boron compd. as a flux. The raw materials are kneaded and dried. The dried raw materials are packed in a heat-resistant container and calcined at 800-1,000 deg.C in a sulfide atmosphere such as H2S, S vapor or CS2 for 1-8hr to obtain a long afterglow blue phosphor suitable for use in high-resolution display tubes.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention is primarily concerned with the development of computer terminals and the power of computer terminals.

B. Prior Art and Problems Display tubes for computer terminals whose main purpose is to display characters and graphics are required to have high resolution in order to display small characters clearly. For high-resolution monitor televisions, the scanning speed of the electron beam that irradiates the phosphor coating on the face plate of the display tube is slowed down as a means of narrowing the frequency bandwidth of the video signal amplification circuit and increasing the resolution. It has been adopted. If the scanning speed of the electron beam is kept constant and the resolution of the display tube is increased, it is necessary to design the frequency band of the video signal amplification circuit of the monitor television to be wider in proportion to the resolution.

For this reason, monitor televisions with high-resolution display tubes have an amplification band of several tens of MHz to 100 MHz, which is several times to more than ten times wider than that of ordinary home televisions. This complicates the video signal amplification circuit, limits the arrangement of components, requires high-speed semiconductors, and requires extremely sophisticated design and assembly techniques, making monitor televisions extremely expensive. I have to.

In addition, there are restrictions on the frequency band of video signal amplification circuits,
Unless the scanning speed of the electron beam is slowed down, high-resolution display tubes capable of displaying ultra-fine characters cannot be put into practical use. When the frequency band of the video signal amplification circuit is narrowed and the scanning speed of the electron beam is slowed down, flickering occurs on the screen. Therefore,
In order to put a high-resolution display tube into practical use, in order to prevent flickering, the 10% afterglow time (the time required for the luminance to drop to 10% of the excitation brightness after excitation stops) is required to prevent flickering. A phosphor that is several tens to hundreds of times longer than the phosphor used in the tube is required.

Conventionally, as phosphors that can be used in the high-resolution display tube, manganese- and arsenic-activated zinc silicate green-emitting phosphor [Zn25 i O4:Mn,As], manganese-activated zinc orthophosphate red-emitting phosphor [Zn5 ( poa)
2:Mn], manganese-activated cadmium chloride orthophosphate orange-emitting phosphor [Cd5C1(P O4) 3
: Mn] etc. are known.

As is well known, display tubes that emit white light,
In order to obtain a color display tube, red-emitting phosphor, blue-emitting phosphor and green-emitting phosphor are essential,
In order to obtain the above-mentioned high-resolution display tube, it is strongly desired to develop a practical long-afterglow blue-emitting phosphor.

The lack of practical use of blue-emitting phosphors with sufficient afterglow properties and luminance has hindered the transition from monochrome to color ultra-high resolution display tubes.

Phosphors have been developed that emit blue light when stimulated by electron beams and yellow light during afterglow. This phosphor is a silver-activated zinc sulfide phosphor (
Zn25, a long afterglow green phosphor, is added to ZnS:Ag).
iOa:Mn, As, and Zrz(PO4)2:Mn, which is a long afterglow red phosphor, are mixed, and the blue emitting phosphor is given afterglow by the red and green phosphors.

Therefore, although the emitted light color of this phosphor is blue, the afterglow color is yellow, which has the drawback of reducing the color purity of all emitted colors.

In contrast to this red, blue, and green mixed phosphor, a phosphor whose emission color and afterglow color are blue has been proposed. (JP-A-58-79814, JP-A-58-83084, JP-A-58-83085, JP-A-58-12)
(No. 0521, Japanese Unexamined Patent Publication No. 58-129083) These phosphors use zinc sulfide ZnS as a matrix, silver as an activator, and either Ga or In as a first co-activator. , Au, or Cu as the second co-activator, and halogen, Al, or the like as the third co-activator.

These phosphors have zinc sulfide (ZnS) as a matrix, and phosphors with this composition emit blue light and have a blue afterglow color, but the luminance is lower than that of conventional short afterglow blue phosphors. In addition, the burning characteristics, which are important for long afterglow phosphors, are poor, and the linearity of the luminance with respect to the electron beam current is poor, making it impossible to achieve luminance proportional to the current density. It has not yet been put into practical use.

C0 Problems to be Solved by the Present Invention As mentioned above, long-afterglow phosphors are used in high-resolution display tubes to clearly display characters, graphics, etc. on the screen, but they are not suitable for this type of use. With phosphors, certain parts of the phosphor coating film are strongly irradiated with electron beams, and this tends to cause localized brightness reduction due to deterioration (burning), resulting in a decline in the uniform display ability of the display tube. This causes a shortened lifespan.

Colors used in regular home televisions,
Alternatively, in monochrome television cathode ray tubes, the entire surface of the phosphor film is irradiated with electron beams evenly, so burning occurs uniformly and is not much of a problem. However, in high-resolution display tubes for this type of use, the local current density in specific parts is high, the scanning speed of the electron beam is slow, and the irradiation time of the electron beam is long, so burning characteristics are particularly important.

Furthermore, another important condition is that even if it is a long-lasting phosphor, it must have high luminance. However, in principle, a long afterglow phosphor has lower luminance than a short afterglow phosphor. This is because the long afterglow phosphor emits light even after the electron beam stimulation has stopped, so it emits energy given by the electron beam over a long period of time.

In other words, when light is emitted for a short period of time, such as with a short afterglow phosphor, the amount of light emitted per unit time is large, resulting in a high emission brightness. With afterglow phosphors, the amount of light emitted per unit time is small, resulting in low luminance.

Another problem is that in order to increase the luminance of phosphors with low emission brightness, the current density of the electron beam is increased, but it is difficult to increase the current density and strengthen the electron beam stimulation of the phosphor. The more the temperature increases, the more likely it is that burning will occur. That is, when the luminance of the emitted light decreases, the burning characteristics also deteriorate, significantly degrading the characteristics of the entire phosphor. From this, it goes without saying that afterglow phosphors have a long afterglow time.
High luminance is also an extremely important condition.

Yet another condition is current characteristics. The electric value characteristic is the linearity of luminance with respect to the current density applied to the phosphor. In an ideal phosphor, when the current density is increased by 10 times or 100 times, the luminance of the luminescent material increases linearly by 10 times or 100 times in proportion to the current density. This state is said to be that the current characteristic of luminous efficiency is 100%. However, the luminance characteristics of existing phosphors do not change linearly with respect to current and are lower than this. The main cause of the current characteristic deterioration is that when the current density is increased or decreased, the emission color shifts. Emission brightness is the product of the emission energy multiplied by the standard observer's color matching function and integrated over visible wavelengths, so if the emission color changes, it no longer shows the expected brightness. If color shift occurs due to an increase or decrease in current density, it causes a decrease in color reproducibility with respect to the brightness of the screen of the display tube, which is also undesirable.

As mentioned above, in addition to favorable afterglow characteristics, the phosphors used in high-resolution display tubes have high luminance and
It is desired that the burning characteristics and current characteristics are good. An important object of the present invention is to provide an afterglow phosphor that has both blue emission color and afterglow color, and has excellent afterglow properties, emission brightness, burning properties, and current properties.

D. Means for Solving Conventional Problems The phosphor of the present invention uses zinc cadmium sulfide [(Zn, Cd)S as a matrix, Ag as an activator, Ga, In, T1. Sn, As
, Pb, Sb, B1, and P as the first coactivator, and at least one of Cl, Br, I, F, and Al as the second coactivator.

Depending on the content of CdS in the matrix, the afterglow time, luminescent color,
Emission brightness changes. If the amount of CdS is too large or too small, the afterglow time will decrease. From this, CdS is 0.1 to 20% by weight, preferably 1 to 15% by weight based on the base material.
determined.

Emission brightness and emission color change depending on the content of Ag, which is an activator. The luminance of luminescence decreases if the amount of activator is too large or too small.

The amount and type of activator depend on the luminance required for the phosphor,
The optimum value is determined in consideration of the luminescent color and raw material cost, but it is usually 1 x 10-5 to I x 10-1 relative to the base material.
Weight %, preferably 5 x 10-4 to 5 x 10-2 ff
The i amount is determined as %.

The first co-inactivating agent is Ga, In, TI+Sn.

As, Pb, Sb, Bi, and P are contained in the sulfide matrix and adjust the afterglow time. These first co-activators are:
In a preferred range of use, Cd at a specific content
The S content has the effect of further increasing afterglow. or,
The afterglow time increases as the content increases.
On the other hand, the luminance of backlighting decreases. Furthermore, if the type of material contained changes, the afterglow time, luminance brightness, and luminescent color will change.

Therefore, the type and content of these first co-activators are selected depending on the afterglow time, luminance brightness, and luminescent color required of the phosphor, and the content is determined based on the parent material. It is usually determined to be .theta..about.3.times.10.sup.-10" 1% by weight, preferably I.sub.XIO-6.about.5.times.10.sup.-2" by weight, based on the sulfide.

Furthermore, Cl, Br, I which is a second co-activator.

The luminance and color of F and Al change depending on the type and content of the material, and the luminance decreases if the content is too high or too low from the optimum value. Therefore, these materials are
The optimum value is determined based on the required luminance and color of the emitted light. CL Br, T and F are usually 5 x 10-5 to 5 x IQ-1% by weight, preferably 5 x IQ-1, based on the base sulfide.
The content of O-4 to 5x10-2% by weight and Al is contained in the range of 5x10-4 to 5x10-2% by weight based on the base sulfide.

E. Preferred embodiment The phosphor of the present invention is manufactured by the method described below.

As the phosphor raw material, (a) both ZnS and CdS as the matrix raw material, (b) Ag as the activator, (c) Ga, In, S when using the first co-activator.
n, Tit Pb+ Sb, Bi, P chloride and A S
(iv) Cl, Br, I as the second co-activator.

At least one of the ammonium salt and sodium salt of F, or the chloride, sulfate, and nitrate of aluminum is used.

Furthermore, H2PO4, BCl3 is preferably used as a fluxing agent.
, BF3 etc. are used. The amount of orthoboric acid used as a flux is 5 x 10-4 to 5 x 10-2 based on the matrix.
Weight % is appropriate.

The phosphor of the present invention is prepared by kneading the above-mentioned raw materials in an optimum amount, drying the mixture, filling the resulting phosphor raw material mixture into a heat-resistant container such as a quartz crucible or a quartz tube, and firing the mixture. Firing is in a hydrogen sulfide atmosphere.
The test is carried out in a sulfidic atmosphere such as a sulfur vapor atmosphere or a carbon disulfide atmosphere. A suitable firing temperature is 800°C to 1100°C. The firing time varies depending on the firing temperature, the amount of the phosphor raw material mixture, etc., but 1 to 8 hours is appropriate. After firing, the obtained fired product is thoroughly washed with water, dried, and sieved to obtain the phosphor of the present invention.

Example 1゜Zinc sulfide ZnS 900g Cadmium sulfide CdS 100g Silver nitrate
AgNO30, 13g Gallium chloride GaC
l3 0.8g Sodium chloride NaCl
10g orthoboric acid 318g H2BO The above raw materials were made into a water slurry, sufficiently kneaded and dried, and appropriate amounts of sulfur and activated carbon were added to the obtained phosphor raw material mixture, and the mixture was filled into a quartz crucible. After capping the quartz crucible,
It was placed in an electric furnace and fired at a temperature of 950°C for 3 hours.

After firing, the obtained fired product was thoroughly washed with water, dried, and sieved. In this way, (Zn, Cd)S :A
g, Ga, Cl phosphor was obtained.

This phosphor is based on (Zn, Cd)S, which is the base material.
It contained 8 x 10-3 weight percent silver, 1.6 x 10-2 weight percent gallium, and 5 x IO-3 weight percent chlorine.

As shown in Table 1, the above phosphor has a luminescent color of ClE
In the X value and y value of chromaticity display, x=0.147, y=Q
.
The emission brightness is extremely high at 63.5% compared to the 5%), and the afterglow time after 10 seconds after the electron beam fill starts and stops (5%) is an excellent value of 3 milliseconds. Ta.

In Table 1, short afterglow blue wandering phosphor (Z
nS: Ag, Cl) are the raw materials of Example 1 or I"l CC
, l S and Ga Cl 3 were used, but the sample was manufactured under the same conditions as in Example 1.

Moreover, conventional long-afterglow blue-emitting phosphors (ZnS:Ag, G
a, Cl) is 1 x 10-'' weight% silver, 1.1 x 10-2 weight % Ga, l x 1O~4 weight %
A phosphor with preferable characteristics as a conventional product containing Ct was used.

In the manufacturing process, this phosphor is made of GaCl?, which is the raw material for the first #activator. Adjust the mixing amount of t11
Emission luminance and afterglow time were measured. The results are shown in FIGS. 1 and 2.

As is clear from Fig. 1, the luminance decreases as the Ga content increases, but the afterglow time is 20% when the GaO-activated mold is 2.5xxo1~t and 4X10-1% by weight. Over milliseconds, 2.2×1O-(~8X10-2
It was 40 milliseconds or more in the weight% range.

Fruit 1 store example 2゜Zinc sulfide Z n 5 900 g Cadmium sulfide Cd S 100 g Silver nitrate A, g N O30-73 g Indium chloride 1 nclz 0.4 g Aluminum nitrate ~1 (Nl) 3hQ1121'+ 0,56
g Salt f Hyammonium NF (,tC!
10g of the above raw material was treated in the same manner as in Example 1 except that it was calcined at 1020°C for 2.5 hours (Zll, C(
1) S:, Ag, In, Al phosphor was obtained.

This phosphor has a matrix of (Zn, Cd)S:
, 8 x 10-3 wt% Ag, 1.6 x 10-2 wt% In, 6.5 x 10-3 wt% A+.

As shown in Table 2, this phosphor has a luminescent color of CrE
In the chromaticity display x hα, V value, x = 0.148, y
= 0.069, which shows blue light emission, compared to the conventional long afterglow blue light emitting phosphor (ZnS: 2.In).

Compared to the relative luminance (=10.0%) of 1), the luminance is considerably higher at 52.6%, and the 10% afterglow time after stopping electron beam excitation is 80 mm. seconds and F ([
α was shown.

In Table 2, the conventional short afterglow blue emitting phosphor (ZnS
:, Ag, Al) are CdS and InC from the raw materials of Example 2.
A prototype was produced under the same conditions as in Example 2, except for l3.

In addition, conventional long-afterglow blue-emitting phosphors (ZnS:Ag,
In, Al) is 1 x 10-2% by weight of Ag based on the matrix; 1. , I X 10-2fffffi%
A phosphor having favorable characteristics was used as a conventional product containing 1 ton% of In, I x 10-''1.

Example 3゜Zinc sulfide ZnS 950g Cadmium sulfide CdS 50g Silver nitrate
AgNO30, 13g Crium Hanride T
lCl3 0.15g aluminum nitrate to 1 (Nl
) q) 39To00, 56 g enriched ammonium
N ) (jB r 8 g of the above raw materials 100
(Zn, Cd)S:Ag, T1. An Al phosphor was obtained.

This phosphor is a parent substance (Zn-cd)Sζ
Te, 8, OX ] 0 ”iJ'zff1%cl)
AZ, 8.0XlO-3 wt% Tl, 6. ;3×
10-1 o-=contained % by weight of He1.

Table 3 shows the conventional short afterglow blue emitting phosphor (ZnS
:, Ag, Al) are CdS, T from original 1 of Example 3.
This sample was produced under the same conditions as in Example 3 except for lCl.

In addition, conventional long-afterglow blue-emitting phosphor (ZnS:A g
, G a , A I ) is I
0-2% by weight of Ag, 1. 1 x 10-2% by weight of Ga,
A phosphor containing 1% A1 by weight of 1X1O-4 was used as a conventional product with favorable characteristics.

When the mixing amount of TlCl3, which is the raw material of this phosphor, was measured and the relative luminance and afterglow time were measured, the characteristics shown in FIGS. 3 and 4 were obtained. As is clear from Figure 1 and Table 3, the TI example activity is 1 x 104 to 4 x 10
-1 weight]% range, afterglow time is 20 milliseconds or more, 3.5
The time was 40 milliseconds or more in the range of xIO-' to IX 10-1% by weight.

The content of the activator is determined based on the most continuous value of tk, taking into consideration the emission color and luminance required for the phosphor, as well as the type of matrix, but it is usually determined by 1 x 10 increments for the matrix. ~I x 10-1% by weight
, preferably determined to be between 5 x 1n-4 and 5 x 10-2% by weight.

The content of the first co-activator is within the range described above.

That is, usually O~; 3 x 10-10-1% by weight, preferably
Therefore, from the characteristics shown in FIGS. 1 to 6, the weight percent of I.times.10 to 5.times.10 is determined.

By the way, in Figures 1 to 6, the relative luminance with respect to the content of the first co-activator is expressed assuming that the phosphor not containing the first co-activator is 100%. did.

In addition to the Cl and Br used in the above embodiments, 1. F'', Al, etc. can be used. C1, Br, 1.F, l\1 can be used not only alone, but also in combination with Both are possible.

If the first and second co-activators contain 171 types of activators together, the content of the first or second co-activator with respect to the matrix Zn, S is the same as the powder content of the first or second co-activator. Total amount: l!
l will be adjusted.

Effects of the F1 Invention The fact that the phosphor of the invention has superior luminance, afterglow time, and preferred luminescent color compared to conventional long-afterglow blue-emitting phosphors is shown in Tables 1 to 1. It is described in Table 3. That is, the long-afterglow blue-emitting phosphor of the present invention has a long afterglow blue-emitting phosphor that is 1.
．． It had extremely excellent characteristics, having a relative luminance of 3 to 21a and an afterglow time of about 1.1 to 3 times.

7 to 15 show the afterglow characteristics, burning characteristics, and current characteristics of the phosphor of the present invention prototyped in Example 1.2.3.

In FIGS. 7, 10, and 13, curve a is shown in Table 1 for the conventional short afterglow blue-emitting phosphor (a).
: △, 4 shows the characteristics of Cl phosphor, and the first curve shows the conventional long afterglow property i? The body of the color-emitting firefly (b) is shown as ZnS:, bare, (, -: :t, Cl
Curve C indicates the characteristics of the phosphor of the present invention (Zn, Cd), which were prototyped in all four experiments.
J+.

The characteristics of Cl phosphor are shown.

8, 21 (71, 1 curve a in FIG. 1-1 is shown as a conventional short afterglow blue light emitting phosphor (a) in Table 2.ZnS:Ag , shows the characteristics of the A I phosphor, and the curves are shown in Table 2 for the conventional long-afterglow blue-emitting phosphor (1)).
, curve C shows the characteristics of the phosphor (Zn, Cd) of the present invention prototyped in Example 2.
, In, shows the afterglow characteristics of Al phosphor.

In Figures 9, 12, and 15, Ill We a
To t.

Table 3 shows the characteristics of the conventional short afterglow red color emitting phosphor (:L) of ZnS:Ag,Cl phosphor. blue-emitting phosphor (b
) ZnS:Ag, T I .

Curve C shows the characteristics of the Al phosphor. The phosphor of the present invention (Zn, Cd) S: AP, which was prototyped in Example 3.

The characteristics of T I and A I phosphors are shown.

The burning characteristics shown in the 1011th to 12th fm are as follows:
It was measured under the following conditions. Fluorescent material for measurement is precipitated on Virex glass, acrylic lacquer filming,
The phosphor coating film was forcibly degraded by applying a metal back and scanning the phosphor coating film with an electron beam of cm2 at a voltage of 27 kV and a current density of 20 tt8 for a specific time using a phosphor brightness IQI measuring device. Obtained. The phosphor coating film, which has not been scanned with an electron beam, is heated by an electron beam of φ11 with a voltage of 27RV and a flow angle of 0.5μA/cm2, and the luminance at this time is set as 100%.
At the same voltage and current level, the luminance of the phosphor coating film that has been forcibly degraded is measured, and the relative luminance is expressed as a percentage.

This was defined as the burning characteristic for a specific time.

The current characteristics shown in FIGS. 13 to 15 were measured under the following conditions. The luminance when the current density is 0.051+A/Cm2 is 100%, the current density is 10 times,
1 (l f' When multiplied by 1, the luminance remains unchanged at 1
Assuming Riyu's phosphor, which will be 0x and 100x.
, that L'l! ! When the luminance of the target phosphor was 100% at each fi flow window, the relative luminance of y was defined and measured as an fL current characteristic.

As is clear from the afterglow characteristics shown in FIGS. 7 to 9, it is clear that the phosphor of the present invention exhibits superior luminescence brightness and afterglow characteristics compared to conventional long-afterglow phosphors. And,
It is also clear from FIG.

In actual use, if the luminance is low, the current density is increased to increase the luminance. Does the wood-invented phosphor with high luminance have low luminance? Compared to conventional afterglow phosphors, it takes only one low current density to obtain the desired brightness of a display tube. Its characteristics surpass those of conventional phosphors.

The current characteristics are shown in FIGS. 13 to 15, and the curves are the characteristics of a conventional afterglow blue-emitting phosphor. This is J
It is clear that the current characteristics of the phosphor of the present invention are also superior to that of the conventional 1 mil blue-emitting phosphor.

[Brief explanation of drawings]

Figures 1 to 6 are graphs showing the relative luminance and afterglow time of the phosphor of the present invention with respect to the amounts of potassium, indium, and thallium, and Figures 7 to 9 are graphs showing the luminescence versus afterglow time of the phosphor. Graphs of brightness, Figures 10 to 12 are graphs of relative luminance against electron excitation time,
Figures 13 to 15 are graphs of relative luminance versus f flow density.

Claims (8)

[Claims] (1) (Zn, Cd)S (zinc cadmium sulfide) is used as a matrix, Ag (silver) is used as an activator, and the first co-activator is
Ga (gallium), In (indium), Tl (thallium), Sn (tin), As (arsenic), Pb (lead), Sb (
antimony), Bi (bismuth), and P (phosphorus), and the second co-activator is Cl (chlorine),
Br (oxaline), I (iodine), F (fluorine), A1
An afterglow phosphor characterized by being at least one of (aluminum). (2) The content of cadmium sulfide is 0 relative to the sulfide matrix.
．． The afterglow phosphor according to claim (1), which has a content of 1 to 20% by weight. (3) The silver content of the activator is 1×1 with respect to the sulfide matrix
The afterglow phosphor according to claim (1), which has a content of 0^-^5 to 1 x 10^-^1% by weight. (4) The content of the first co-activator is 0 to 3 x 10^-^1% by weight based on the sulfide matrix.
The afterglow phosphor described in section 1). (5) Claim (1), wherein the content of the first co-activator is 1 x 10^-^5 to 3 x 10^-^1% by weight based on the sulfide matrix. Afterglow phosphor. (6) The content of Cl, Br, I, F, which is the second co-activator, is 5 × 10^-^5 to 1 × 10 with respect to the sulfide matrix.
^-^1% by weight of the afterglow phosphor according to claim (1). (7) The content of Al, which is the second co-activator, is 5 x 10^-^4 to 5 x 10^-^1% by weight based on the sulfide matrix.
The afterglow phosphor according to claim (1). (8) The afterglow phosphor according to claim (1), which contains a B (boron) compound as a fluxing agent.